1. Field of the Invention
The present invention relates to a power supply device for supplying an electric power to sensors and a control device mounted to an automatic door so as to ensure a safe operation of the automatic door.
2. Description of the Related Art
A general construction of an automatic door, for example, double doors, is illustrated in FIG. 1. Doors 4 and 5 are suspended from a transom (base) 1 fixed to a building side through slide rollers 2, 2 and 3, 3, and pulleys 6 and 7 are pivotally supported at both ends of the transom 1 so as to extend a belt 8 therebetween. A lower part and an upper part of the belt 8 are respectively engaged with the doors 4 and 5 and the pulley 6 is rotationally driven by a motor unit 9, thereby opening and closing the doors 4 and 5. The movement of the doors 4 and 5 is controlled by a sensing signal of a touch switch 10 or a proximity switch.
In a case in which the doors 4 and 5 are respectively opened and closed under the control of a movable sensor attached to the door, such as the above touch switch 10, it is required to use a helical cord 12 as used in a telephone and further to bring the sensor in contact with a trolley wire 11 in the same manner as a trolley train in order to supply an electric power from a power source 13 to the sensor such as the touch sensor 10. However, the trolley wire 11 is apt to be damaged since the frequency of the opening and closing of the doors 4 and 5 is very high. A method of solving the above problem is disclosed in Japanese Utility Model Publication (KOKOKU) No. 28835/1988. In this method, a door is provided with a battery, and an oscillator mounted to the door which transmits a signal from a touch switch such as a light signal to a photo-sensitive control device in a transom, thereby controlling the movement of the door. In this case, it is not necessary to supply electric power from an outer power source. However, since the amount of the electric power consumed is large, in consideration of safety, it is necessary to increase the capacity of the battery or frequently replace batteries.